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.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Copyright (C) , Michael Neuffer <neuffer@mail.uni-mainz.de>
.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
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.\"
.TH proc_scsi 5 2024-05-02 "Linux man-pages 6.9.1"
.SH NAME
/proc/scsi/ \- SCSI
.SH DESCRIPTION
.TP
.I /proc/scsi/
A directory with the
.I scsi
mid-level pseudo-file and various SCSI low-level
driver directories,
which contain a file for each SCSI host in this system, all of
which give the status of some part of the SCSI IO subsystem.
These files contain ASCII structures and are, therefore, readable with
.BR cat (1).
.IP
You can also write to some of the files to reconfigure the subsystem or
switch certain features on or off.
.TP
.I /proc/scsi/scsi
This is a listing of all SCSI devices known to the kernel.
The listing is similar to the one seen during bootup.
scsi currently supports only the \fIadd\-single\-device\fP command which
allows root to add a hotplugged device to the list of known devices.
.IP
The command
.IP
.in +4n
.EX
echo \[aq]scsi add\-single\-device 1 0 5 0\[aq] > /proc/scsi/scsi
.EE
.in
.IP
will cause
host scsi1 to scan on SCSI channel 0 for a device on ID 5 LUN 0.
If there
is already a device known on this address or the address is invalid, an
error will be returned.
.TP
.IR /proc/scsi/ drivername /
\fIdrivername\fP can currently be NCR53c7xx, aha152x, aha1542, aha1740,
aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000, pas16, qlogic,
scsi_debug, seagate, t128, u15\-24f, ultrastore, or wd7000.
These directories show up for all drivers that registered at least one
SCSI HBA.
Every directory contains one file per registered host.
Every host-file is named after the number the host was assigned during
initialization.
.IP
Reading these files will usually show driver and host configuration,
statistics, and so on.
.IP
Writing to these files allows different things on different hosts.
For example, with the \fIlatency\fP and \fInolatency\fP commands,
root can switch on and off command latency measurement code in the
eata_dma driver.
With the \fIlockup\fP and \fIunlock\fP commands,
root can control bus lockups simulated by the scsi_debug driver.
.SH SEE ALSO
.BR proc (5)
